The affected cameras in the company's EOS 650D range contains a substance which can react to humidity to produce a substance known as dimethyldithiocarbamate or "zinc bis" that causes the camera's rubber grip surfaces to turn white and is some cases can cause skin irritation, the BBC reported Wednesday.
Unconfirmed reports put the number of affected cameras at around 68,000.
Canon said a production run of the cameras in June contained a "higher than usual" level of a substance used to "vulcanize," or harden, the rubber grip.
If gripped by perspiring hands, the resulting humid condition is said to produce the zinc bis.
Canon has created a Web site which allows users to enter their camera's serial number and see if their device is in the affected batch, and is offering free repair for units with the problem.